Structure-property relationship individual phases

Characterization of polymer orientation is most often accomplished via X-ray techniques which are suited to crystalline and paracrystalline regions (i-d). However, semicrystalline polymers present a complex system of crystalline, amorphous, and intermediate pluses ( -d) and complete characterization of semicrystalline polymers can only be achieved by application of a variety of techniques sensitive to particular aspects of orientation. As discussed by Desper (4), one must determine the degree of orientation of the individual phases in semicrystalline polymers in order to develop an understanding of structure-property relationships. Although the amorphous regions of oriented and unoriented semicrystalline polymers are primarily responsible for the environmental stress cracking behaviour and transport properties of the polymers, few techniques are available to examine the state of the amorphous material at the submicroscopic level. 

This section deals with the physical properties (other than the crystal structures and phase relationships which were discussed previously) of the allotropes a-, /3- and y-Ce. Because of the paucity of information little or nothing will be discussed about the properties of the allotropic phases S-, a - and a"-Ce. Much of the published information on the properties of a-, /3-, and y-Ce at low temperatures (< 273 K) and low pressures (< 0.5 GPa) will be ignored primarily because the measurements were made on samples containing two or three phases and the data are difficult to partition uniquely into the contributions of the individual phases. Even in cases where careful attempts were made to extract useful data the-information was ambiguous and generally not meaningful. 

Often the goal in the development of a composite for any application is to combine the bulk properties of various phased components into a cohesive, uniform structure. It is not surprising then that the interface between two phases within the composite, frequently a liquid and a solid, is a vital relationship that has numerous downstream effects. The surfaces of the individual components can be altered and tailored in numerous ways, before combining them in a composite form, to achieve desired properties of the individual components within the composite or the resultant composite structure as a whole. 

Although the high-temperature superconducting phases are formed from insulating materials by the introduction of defects, the precise relationship between dopant, structure, and properties is not fully understood yet. For example, in most of the cuprate phases it is extremely difficult to be exactly sure of the charges on the individual ions, and because of this the real defect structures are still uncertain. 

Basic science in the general field of macromolecules includes the principles of their synthesis the investigation of the size and structure of individual molecules in solution, and the relationship between structure and properties in the bulk phase. Approximately 450 scientists in 90 laboratories all over the world devote the major portion of their time to basic science in the subject field. The results of their work are published in about 150 technical journals which include literature on plastics. Reviewing the literature at present is difficult. The author suggests services which include a weekly news letter, monthly journal for papers, semiannual journal for review articles, and formula and data sheets in addition to regularly appearing monographs, textbooks, and handbooks. 

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